1. Field of the Invention
The present invention relates to an electronic chip component for measurement to be mounted on the surface of a printed board by means of a chip mounter and capable of being engagedly fitted with a measuring probe.
2. Description of the Related Art
Disclosed and described in Jpn. UM Appln. KOKOKU Publication No. 5-27809 is a conventional electronic chip component for measurement, which is mounted on the surface of a printed board and to which a measuring probe can be anchored. This chip component is composed of a metallic plate, one side of which is solderable and the other side of which is not. It is a rectangular tube, as a whole, which is formed by bending the metallic plate so that the surface that is not solderable is inside.
As shown in FIG. 1, more specifically, this chip component 30 is a rectangular tube of stainless steel, which comprises a top section 31 formed of a probe retaining portion, side sections 32 formed of soldering portions, and a bottom section 33 formed of a joint portion to be bonded to the printed board. A slit 33s is formed in the bottom section 33 of the chip component 30, corresponding to the abutting portions of the metallic plate. The inner surface of the chip component 30 is not subjected to surface treatment such as plating, while the outer surface is plated with solder or the like.
In mounting this chip component on the printed board, solder paste is previously applied to predetermined spots on electrodes (lands) of the printed board, and the chip component is placed on the lands by means of a chip mounter. Thereafter, the printed board is heated in a heating oven so that the solder is remelted therein. Soldering is carried out in this mounting position.
Since the outer surface of the conventional chip component is metallized with a solderable metal, solder can easily adhere to the whole outer surface and inevitably cover apertures like snowholes.
Since the whole outer surface of the conventional chip component is solderable, moreover, there is no need of discrimination between the obverse and reverse of the component when the component is mounted on the surface of the printed board. When the chip component, a rectangular tube, is mounted on the printed board, however, the whole base of the chip component inevitably touches the solder paste that is applied to the lands of the board. Accordingly, the pressure from the weight of the chip component that acts on the surface in contact with the printed board is reduced. If the solder is remelted during reflow-soldering process, therefore, the whole chip component floats above the solder.
In this state, the points of application of the surface tension of the solder cannot be settled in specific positions on the base of the chip component. Thus, the irregularity of the surface tension of the solder adhering to the peripheral edge of the chip component acts as a moment around the center of the base of the component. In consequence, the chip component is misoriented over the solder, and may possibly be soldered directly to the printed board.